The present invention relates generally to valves for fluid media, and more particularly to bypass valves.
In the use of practically any sort of machinery with moving parts, it is common practice to provide some sort of lubrication system as part of (or operatively associated with) such machinery. For example, most internal combustion engines include a lubrication system in which oil is pumped through passages within the engine block such that certain moving parts (e.g., pistons, cams, etc.) are lubricated therewith. Substantially all of such lubrication systems include some type of filter which filters out particulates that may be found in the circulating fluid lubricant.
When these filters become clogged with accumulated particulates, it becomes increasingly difficult to continue circulating the fluid lubricant through the filter, giving rise to the need for some way of temporarily bypassing the filter until the filter (or its filtration medium) can be replaced. These methods for temporarily bypassing the filter may take the form of bypass valvesxe2x80x94which may be part of the filter or which may be positioned at some other point in the lubrication circuit apart from the filterxe2x80x94or they may take other forms. For example, U.S. Pat. Nos. 4,099,540 to Papp; 4,127,484 to Walulik et al.; 4,144,168 to Thornton; 4,174,699 to Gill; 4,190,198 to Casuga et al.; 4,246,109 to Manders; 4,304,663 to Manders; 4,399,785 to Mills; 4,402,287 to Cochran; 4,406,784 to Cochran; 4,416,592 to Lindtveit; 4,462,352 to Mills; 4,476,825 to Mills; 4,755,289 to Villani; 5,124,052 to Hardaker; 5,180,490 to Eihusen et al.; 5,193,621 to Manke et al.; 5,339,776 to Regueiro; 5,843,284 to Waters et al.; and 6,096,199 to Covington, all of which are incorporated herein by reference as if set forth herein in full, teach various aspects of bypass valves and/or methods of bypassing a filter in a lubrication or oil circulation/oil pumping system.
Oil filter bypass valves/bypass systems are typically designed to accommodate the aforementioned xe2x80x9cclogged filterxe2x80x9d situation. However, there exists yet another potential problem separate from the clogged filter situation which heretofore has not been addressed in the prior art: namely, the potential for inadvertently circulating metal chips and/or other particulates during the initial running of the engine. Such particulates may be left over from the machining and other manufacturing processes used to create the engine block, cylinder blocks, etc., and may lie hidden or lodged within the galleys and other oil circuits within the engine. After an engine manufacturer produces an engine, the engine is typically run for a short time to make sure the engine is working properly and to conduct certain tests and calibrations. During this initial run, the oil is typically cold, causing a temporary increase in pressure drop (i.e., a perceived increase in pressure, a resistance) across the oil filter. This increased resistance across the filter forces open the normally-closed oil filter bypass valve, thus allowing unfiltered, potentially particulate-laden oil to flow around (rather than through) the oil filter and thence into the engine. This bypass situation occurs not because the filter is clogged, but because of the increased pressure drop across the filter due to the initial low temperature/high viscosity of the oil. Once the oil is sufficiently heated and thinned, the pressure drop/resistance decreases across the filter and the bypass valve closes, thereupon diverting the oil through the filter rather than around it. As mentioned above, this temporary bypassing of the oil filter during the first few cycles of a new engine may cause circulation of metal chips and particulates that may damage various engine components.
It would be desirable, therefore, to provide a bypass valve which performs the normal oil filter bypass function when the filter is clogged, but which also can delay this bypass function during the initial cycles of a newly assembled engine until after the oil becomes sufficiently heated.
The present invention overcomes the disadvantages of the prior art approaches by providing a delayed action bypass valve assembly. This bypass valve assembly comprises: a housing having an inlet and an outlet; a valve member disposed within the housing and being movable between a closed position and an open position; and a slug of material disposed in an initial substantially solid phase in contact with the valve member so as to maintain the valve member in the closed position. The slug of material is subsequently heatable into a substantially softened phase so as to permit the valve member to move into the open position. In the closed position, the valve member is sealably disposed against the housing inlet to prevent fluid flow therethrough, while in the open position the valve member is disposed away from the inlet, thereby permitting fluid flow therethrough.
It is an object and advantage that the present invention provides an initial delay of the bypass action in a bypass valve. When used in conjunction with an engine and its oil circulation system as described herein, an oil filter bypass valve according to the present invention helps to mitigate the effects of any inadvertent circulation of particulate contaminants in the engine during the initial cycles of the engine.